The hyphen's main purpose is to put different words together. They inform the reader that there are two or more elements in the sentence that can be linked with a hyphen, and there are different specific rules that help writers determine whether or not they need to clarify words or phrases with hyphens.
One important rule that writers must remember is that hyphens should never be used in the same way that dashes are used. Dashes are noticeably longer than hyphens, and they are meant to denote an entirely different set of rules. There should also never be any spaces around hyphens when they are used between words.
The first known written instances of hyphens occurred in the works of Dionysius Thrax, and during this time, hyphens were used to join words together that could have otherwise been read separately. The modern introduction of the hyphen originated in 1455 with the publication of a 42-line Bible.
Hyphens also have uses outside of modern grammar, such as when they are used to connect numbers, as in dates, telephone numbers and sports scores, as well as when they are used to hide letters by censorship. Dashes can be used like hyphens in the case of censorship.